I don't know what is taking up most of my space... I don't think
it's the
Ubuntu installation itself. But something is hogging most of the HDD and
leaving me with only 3.2GB free hard disc space.


There are a couple of utilities that tell you where the file space is being
used. I like Filelight. Another is called gdmap. They give a visual
representation of your drive showing where the files are located and the number
of MBs in each directory.

I would also look at your .tmp, .temp directories, .thumbnails directory, and
trash (.local/share/Trash). Kleansweep is also a good tool for this.